If I let my neighbor share my WiFi, can they see my network traffic?

Additional Details

I have a home network with three computers (two desktops connected with ethernet cables to a Linksys router; laptop is wireless). The wireless signal is encrypted and I gave my next-door neighbors my network key so they can wirelessly connect just to check email, do banking, etc. They are not on my home network, but can they still see where I am surfing (such as my bank site with passcodes, etc.)?